Biological weapons, infectious diseases, and environmental pathogens threaten both military and civilian personnel. Current technology lacks the capability to accurately detect the presence of trace amounts of chemical and biological warfare agents quickly and reliably.
Current technologies include those involving detection of analytes labeled with a fluorescent, photo-luminescent, radioactive or enzymatic marker. This requirement includes additional steps and expense to the detection process, a significant disadvantage when prompt detection is necessary.
Another broad category of currently used sensors includes those that employ optical waveguides. Waveguide sensors typically have the disadvantages of high sensitivity to changes in the ambient conditions such as temperature, resulting in undesirable signal to noise ratios.
Other known sensors monitor changes in the intensity of several diffraction orders to detect the occurrence of a biological binding event. However, intensity (irradiance) measurements are not sensitive enough for many applications and are sensitive to noise, resulting in difficulty in relating and quantifying the changes in the detected diffraction irradiance signal to an input stimulus.